Field of the Invention
The present invention relates to an image forming apparatus configured to form an image on a recording medium fed from a stacking portion.
Description of the Related Art
An electrophotographic image forming apparatus is configured to feed a sheet that is placed in a sheet feeding cassette or on a manual feed tray so as to form an image on the fed sheet. In particular, the manual feed tray is widely used to form an image on a cardboard sheet having a basis weight that is not accepted by the sheet feeding cassette, a coated paper sheet, and the like. For example, in Japanese Patent Application Laid-Open No. H07-097079, there is disclosed a drive transmission mechanism using the same drive source for a sheet feeding pickup roller configured to feed a sheet placed on the manual feed tray and for a sheet feeding roller arranged on a downstream side in a conveying direction of the fed sheet. In Japanese Patent Application Laid-Open No. H07-097079, there is proposed the configuration described above for feeding an uppermost sheet on the manual feed tray in a one-by-one manner each time the sheet feeding pickup roller feeds the sheet to vertically rock a support arm for the sheet feeding pickup roller.
Meanwhile, hitherto, first copy output time (hereinafter referred to as “FCOT”) from the pressing of a copy key to output of the first sheet is desired to be shortened. Even when the sheet is fed from the above-mentioned manual feed tray, it is desired to shorten the FCOT.
However, the conventional image forming apparatus is configured to vertically move the sheet feeding pickup roller each time one sheet is fed from the manual feed tray, and wait in an upper-limit position serving as an initial position while a sheet feeding operation is not performed (during a non-sheet feeding operation). Therefore, the sheet feed is delayed by a time period required for the sheet feeding pickup roller to be moved from the initial position down onto the sheet and a time period required for the sheet feeding pickup roller to wait on the sheet until oscillation is stopped so that the sheet feeding pickup roller starts rotating. Thus, there is a problem in that the FCOT is disadvantageously increased by the amount of delay time.